Is what you would call a dumb person, who's big as a tank, with a brain the size of a peanut, very trusting, but easily manipulated, has either a pet dog or hamster named Duckie, sees things a little different than the rest of us, and believes in Bigfoot, and sometimes goes by the name Cornbred.

Example from classic literature:

Rockchild! When I told you to cut the grass, I didn't mean with a pair of scissors!